Asteroid will fly in distance 4.6 times greater than distance between moon and Earth; still distance of 1 800 000 km is enough to spot asteroid with strong binocular today and tomorrow after dusk.
The asteroid was named as 2014 JO25 after being discovered relatively not long time ago. In May 2014 one from astronomers at the Catalina Sky Survey working at the NEO project by NASA (focused on seeking new asteroids with trajectory crossing space near Earth) discovered asteroid with trajectory evaluated as "close to Earth". It was discovered that diameter of the object is 650 m and it will approach to Earth from the side of the Sun on 19th April 2017.
2014 JO25 will be easy to spot due the fact that its magnitude will be around 11 or 10 and its speed which will be probably around 120 000 km/h, what makes observation easier even for not experienced observers. As first evaluations performed today with radio telescope at Arecibo, Puerto Rico, gave surprising results. Asteroid is larger comparing to previous evaluations and is built with two objects: first is 640 m wide, second is 670 m wide with total length of 1300 m. Exact distance from Earth was evaluated for 1 768 239 km.
This flyby is not something what happens every month. In spite of small asteroids which are passing close to Earth every month, object with such size is not very common. Last time when large asteroid passed Earth in distance below five distances to the Moon was Toutatis in 2004. Another asteroid (1999 AN10) will pass only 390 000 km from Earth in 2027.